1. Technical Field
This invention relates to a coffee kettle capable of automatic extraction of tasty coffee liquid by dripping boiling hot water onto coffee powder.
2. Description of the Prior Art
Among conventional methods of obtaining coffee liquid by dripping hot water onto coffee powder, are a so-called drip type wherein water is introduced from the bottom part of a water tank to a heated pipe, heated, and raised by the use of steam generated by nucleated boiling, and dripped onto coffee powder for 10 minutes or so, and a drop-supply type wherein an water tank is provided with a heater and a temperature-release valve and hot water is dripped onto coffee powder placed below the water tank.
However, these methods have by such drawbacks that the temperature of the supplied hot water is low in an early stage because of the introduction of cold water mixed therein, a temperature characteristic which is below 86.degree. C. even at the point of time of the end of supply until when water has gradually become hotter than before, difficulty in elimination of fluctuation in temperature sensing accuracy, and, as the result, a temperature of the supplied hot water is indefinite and low, and these methods do not supply boiling hot water of a high temperature. Therefore, these methods cannot satisfy such requirement as "To drip boiling hot water onto coffee powder and, sufficiently swelling coffee powder, complete extraction within 3 to 4 minutes" which is a key to extraction of tasty coffee liquid.
And, in order to obtain tasty coffee liquid full of flavor and rich taste, known is the utilization of a so-called steaming effect, wherein in the process of coffee essence extraction coffee powder is put into a state that makes easy the extraction of coffee essence by providing a length of time for sufficiently swelling the whole coffee powder with hot water of high temperature and then by supplying hot water once more onto the coffee powder to efficiently extract coffee essence; but a matter satisfying requirements for extraction at the above-mentioned high temperature including such constitution has not yet been realized, thereby genuinely flavorful and rich coffee liquid having been unobtainable.